Switch arrangement for changing transformer voltage ratio



April 22, 1969 E. A GOODMAN ET AL 3,440,586

SWITCH ARRANGEMENT FOR CHANGING TRANSFORMER VOLTAGE RATIO Filed March 21, 1967 Sheet of 2 April 22, 1969 5, GOODMAN ET AL 3,440,586

SWITCH ARRANGEMENT FOR CHANGING TRANSFORMER VOLTAGE RATIO Filed March 21, 1967 Sheet 2 of2 United States Patent Office US. Cl. 336-147 Claims ABSTRACT OF THE DISCLOSURE An arrangement for connecting sections of the primary winding of a distribution transformer alternately in series or parallel to change the transformer voltage in a ratio greater than three-to-one utilizes a pair of series-multiple switches having stationary contacts connected to a different plurality of winding sections and a parallel crank linkage for simultaneously operating both switches.

This invention utilizes and permits changing transformer windings through a higher ratio of voltages than the dual voltage switch disclosed in US. Patent 3,170,048 to Charles E. Glatz and John M. Anderson having the same assignee as the subject invention.

Distribution transformers are frequently provided with dual voltage switches, such as the series-multiple switch of the aforesaid Glatz et al. patent, to change the transformer from a lower voltage ratio to a higher voltage ratio and thus permit use of the same transformer on power distribution systems of different voltages. The primary winding of such a transformer conventionally has a plurality of winding sections which are connected in parallel by the dual voltage switch for the lower voltage and in' series for the higher voltage. The dual voltage switch of the Glatz et al. patent permits connecting three winding sections, including a tap on one winding section, in series or in parallel to allow changing the transformer voltage in a ratio of approximately three to one, for example, from 2400 to 7200 volts, 2400 to 7620 volts, or 7200 to 14400 volts. However, known series-multiple switches do not permit changing the transformer voltage in ratios greater than approximately three to one.

It is an object of the invention to provide a dual voltage switch arrangement which permits change of transformer voltagein ratios exceeding three to one from a single operating handle.

This and other objects and advantages of the invention will be more readily apparent from the following detailed description when considered in conjunction with the accompanying drawing wherein:

FIG. 1 is a schematic circuit diagram of a preferred embodiment of the dual voltage switch arrangement of the invention showing five transformer primary winding sections connected in parallel to provide the lower volt- FIG. 2 is a view similar to FIG. 1 with the five winding sections connected in series to provide the higher volt- FIG. 3 is a horizontal section view through a distribution transformer incorporating the invention and showing Patented Apr. 22, 1969 a pair of dual voltage switches in plan view mounted within the transformer tank;

FIG. 4 is an elevation view of the embodiment of FIG. 3 with the transformer tank wall broken away to better illustrate the mechanical operating linkage for the pair of switches;

FIG. 5 is a view taken along line V-V of FIG. 4;

FIG. 6 is a view taken along line VI-VI of FIG. 4; and

FIG. 7 is a schematic representation of the contact disks of the switches A and B viewed along line VIIVII of FIG. 5.

Referring to FIG. 1 of the drawing, the preferred embodiment of the invention utilizes a pair of dual voltage switches A and -B similar to that disclosed in the aforesaid U.S. Patent 3,170,048 to Glatz et a1. and each having eight stationary contact posts arranged in a circle and a pair of diagonally opposed movable conductive contact means each of which is adapted to electrically engage and bridge a plurality of the stationary contact posts. The stationary contact posts of switch A are designated S1, S2, S3, F2, F3, 26, F1 and 24, and the stationary contact posts of switch B are designated S1, S5, S4, F3, F5, 20, F4 and T. The distribution transformer has five winding sections 1, 2, 3, 4 and 5. The letters S and F designate the start and finish terminals, respectively, of the winding sections and are used in conjunction with numerals to designate both the start and finish of the corresponding winding section and the stationary contact posts to which they are connected, for example, contact post S4 of switch B is connected to the start of winding section 4.

Switch A is adapted to parallel winding sections 1, 2 and 3; switch B is adapted to parallel winding sections 4 and 5. The stationary contact posts S1 constitute one of the line terminals of both switches A and B and are connected together and to the transformer high voltage bushing H1 by a conductor 12 and to the start terminal of winding section 1. Stationary contact post F5 of switch B constitutes the other line terminal and is connected by a conductor 15 to the transformer primary bushing H2, or ground, and to the finish terminal of primary winding section 5. Stationary contact post F3 of switch A is connected by a conductor 13 to stationary contact post F3 of switch B and to the finish terminal of winding section 3.

A jumper conductor 18 connects contact post F3 of switch B to contact post 20. A jumper conductor 21 connects contact post S5 of switch B to contact post T (assuming post T is not connected by conductor 36 (shown in dotted lines) to a tap on winding section 5). A jumper conductor 23 connects stationary contact post S2 of switch A to contact post 24 thereof, and a jumper conductor 25 connects stationary contact post F2 to contact post 26 of switch A.

In order to facilitate the understanding of the invention, the movable contact means are illustrated in the schematic circuit diagram of FIGS. 1 and 2 as a pair of diametrically opposed conductive arcuate members C and D of switch A and a pair of diametrically opposed conductive arcuate members K and L of switch B, but in reality each movable contact C, D, K and L comprises a pair of disk contacts each of which is adapted to bridge between a pair of adjacent stationary contact posts and 3 is mounted on a rotatable insulating contact housing as disclosed in the Glatz et al. patent, and FIG. 7 illustrates that arcuate movable contact means C comprises a pair of disk contacts 30 and 31 and that arcuate movable contact means D comprise a pair of disk contacts 32 and 33. The pair of disk contacts 30 and 32 are in a plane spaced axially from a plane through the disk contacts 31 and 33, and disk contacts 30 and 31 (comprising arcuate contact means C) bridge and electrically connect three stationary contact posts F1, 26 and F3 in the lower voltage parallel switch position shown in FIG. 1, and similarly the pair of disk contacts 32 and 33 (comprising arcuate contact means D) bridge and electrically connect three stationary contact posts S1, S2 and S3 in the lower voltage parallel position. Similarly, each arcuate contact means K and -L of switch B comprises a pair of disk contacts (not shown) similar to those of switch A. Electrical insulation 35 (see FIG. 6) surrounds the lower portion of posts F1 and S3 of switch A and the lower portion of posts F4 and S4 of switch B, as disclosed in the Glatz et a1. patent, so that movable arcuate contact means C (comprising contact disks 30 and 31) only bridges between two contact posts F1 and 24 and movable arcuate contact means D (comprising contact disks 32 and 33) only bridges between a pair of stationary contact posts F2 and S3 when the switches A and B are actuated in the clockwise direction to the series position shown in FIG. 2. Similarly, in the series position, rotatable contact me ans K of switch B only bridges contact post S4 and F3 and rotatable contact means L only bridges contact posts F4 and T.

It will be appreciated that the winding sections 1, 2, 3, 4 and 5 are connected in parallel when switches A and B are in the position shown in FIG. 1 since the start terminals of all winding sections 1-5 are electrically connected, or commoned, and the finish terminals of all winding sections 1-5 are also electrically commoned. Rotatable contact means D bridges contact posts S1, S2 and S3 of switch A, conductor 12 connects posts S1 of both switches A and B together, and contact K of switch B bridges contact posts S1, S5 and S4, thereby connecting the start terminals of all winding sections 1-5 together. Similarly, contact C bridges contact posts F1, 26 and P3 of switch A, jumper lead 25 connects post 26 to contact post F2, conductor 13- connects contact posts P3 of switches A and B together, and jumper conductor 18 connects post F3 of switch B to contact post 20 which engages arcuate contact means L which is in bridging relation with contact post F4 and F5, thereby connecting the finish terminals of all winding sections 1-5 together. It will be appreciated that switch A parallels winding sections 1, 2 and 3; that switch B parallels winding sections 4 and 5; that conductor 12 connects start posts S1, S2 and S3 of switch A to start posts S4 and S5 of switch B; and that conductor 13 connects finish posts F1, F2 and P3 of switch A to posts F4 and F5 of switch B. Similarly, in the series position shown in FIG. 2, switch A connects winding sections 1, 2 and 3 in serial relation; switch B connects winding sections 4 and 5 in series; and conductor 13 connects the two switches A and B in cascade.

When the dual voltage switches A and B are actuated in the clockwise direction to the higher voltage series position shown in FIG. 2, the primary winding sections 1-5 are connected in a series circuit which may be traced from transformer primary lead H1, post S1 constituting the line terminal of switch A, conductor 12, post S1 of switch B, winding section 1, post F1 of switch A, arcuate contact means C to post 24 of switch A, jumper conductor 23, contact post S2 of switch A, winding section 2, post F2 of switch A, arcuate movable contact means D of switch A, post S3 of switch A, winding section 3, post F3 of switch A, conductor 13, post F3 of switch B, movable contact K of switch B, post S4 of switch B, winding section 4, post F4 of switch B, arcuate movable contact 4 means L, post T of switch B, jumper conductor 21, post S5 of switch B, winding section 5, post P5 of switch B to transformer lead H2 or ground.

Such arrangement permits switching windings of a transformer in an exact voltage ratio of 5 to 1, for example, from 2400 to 12,000 volts. If it is desired to switch the windings in a ratio which is not an integer multiple of the lower voltage, for example, from 2400 to 11,400 volts, one of the winding sections such as winding section 5 can be provided with a tap T connected by a conductor 36 (shown in dotted lines in FIGS. 1 and 2) to stationary contact post T of switch B, and the jumper conductor 21 of switch B omitted. With such arrangement the post F4 is connected by arcuate movable means L to post T and to the corresponding tap T on winding section 5 in the series position shown in FIG. 2, only the portion of winding section 5 between tap T and the tfinish terminal is in series circuit with winding sections 1-4, the portion of winding section between the start terminal and tap T is inactive, and the voltage may, for example, be changed in the ratio of 2400 to 11,400 volts rather than 2400 to 12,000 volts as described for the preferred embodiment.

Referring to FIGS. 3-6, the switches A and B are preferably immersed within the transformer oil and supported internally of a cylindrical transformer casing 40 on an elongated support bracket -41 bolted to mounting pieces 42 which are affixed by bolts threaded within internally tapped lugs 44 welded to the internal surface of casing 40. The mounting and actuating means for switches A and B are similar and only those for switch B will be described. The crosspiece 45 of each of a pair of U-shaped switch holders 46 are welded in spaced relation to support bracket 41. The free ends of the legs of the U-shaped holder 46 fit within rectangular indentations in the circular insulating front plate 48 of a switch B as illustrated in FIG. 6. A stub shaft 49 is aflixed by a cotter pin 50 to the tubular shaft portion 52 of the movable contact disk holder 53 which passes through a central bore 54 in stationary insulating plate 48, and stub shaft 49 extends through clearance holes in switch holder 46 and in support bracket 41 and has a collar 56 aflixed thereto by a roll'pin 57 on the opposite side of support bracket 41 from the switch to mount the switch on support bracket 41.

The switches A and B are simultaneously operated between series and parallel positions by a parallel crank four bar linkage actuated by a single handle 66. A radial crank, or operating arm 59, is welded at one end to stub shaft 49 and is pivotally joined at its opposite end by a bolt and nut connection to one end of a movable connecting rod 60 of the four bar operating linkage. Connecting rod 60 has a similar pivotal connection at its opposite end to the radial operating arm, or crank 59, of switch A. Connecting rod 60 also has a similar pivoted connection adjacent its midpoint to a radially extending switch actuating member 61 which is affixed, preferably by welding, at its lower end to operating shaft 62. A tubular mounting flange 63 may extend through an aperture in, and be welded to, the sidewall of transformer casing 40, and the switch operating shaft 62 extends through mounting flange 63 and may fit within the axial opening in an annular collar 64 of the switch operating handle assembly 66 and be affixed thereto by a roll pin. Switch operating shaft 62 may have circumferential grooves which receive resilient O-ring gaskets (not shown) compresssed against the internal surface of mounting flange 63 to prevent leakage of oil from transformer casing 40.

Manual actuation of operating handle 66 rotates switch operating shaft 62 and effects translation of connecting rod 60 lengthwise thereof, thereby resulting in simultaneous rotation of stub shafts 49 of switches A and B and operation of these switches between the series and paralle positions.

While the preferred embodiment of the invention has been illustrated and described as utilizing two switches to connect five winding sections in series or parallel, the invention is not so limited and also comprehends utilizing a greater number of switches to connect a greater number of winding sections in series or multiple. For example, in accordance with the invention three switches may be used to connect seven winding sections between series and multiple to provide voltage ratios between approximately 5 to 1 and 7 to l. The preferred embodiment describes all winding sections as being identical, but the invention also comprehends use of one winding section with more turns than the others so that, in the series position, a voltage can be obtained which is higher than an integer multiple of the lower voltage provided in the parallel switch position.

While only a single embodiment of the invention has been illustrated and a few alternative embodiments described, many variations and modifications will be apparent to those skilled in the art, and consequently it is in tended in the appended claims to cover all such modifications and variations which are within the true spirit and intent of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In combination with a transformer having a plurality of winding sections,

a plurality of switch means for alternately connecting a plurality of said winding sections in series and parallel and each said switch means connecting a dilferent plurality of said winding sections,

a parallel crank linkage for simultaneously operating all of said switch means between said series and parallel positions,

and means for paralleling all of said switch means when they are in the parallel switch position and for cascading them when they are in the series switch position.

2. In the combination defined by claim 1 wherein each switch means has a plurality of start stationary contacts connected to the start terminals of the corresponding plurality of winding sections and a plurality of finish stationary contacts connected to the finish terminals of said corresponding winding sections and having start and finish rotatable contact means operated by said linkage and adapted to respectively bridge said plurality of start and said plurality of finish stationary contacts in the switch parallel position.

3. In the combination defined by claim 2 wherein each said rotatable contact means in the series switch position disengages from all but one of said plurality of stationary contacts engaged by it in the parallel switch position and bridges said one stationary contact and an adjacent stationary contact to electrically common stationary contacts connected to start and finish terminals of different winding sections and connect them in cascade.

4. In the combination defined by claim 3 and including conductor means for interconnecting a start stationary contact of one of said switch means with the corresponding start stationary contact of all the other switch means and conductor means for interconnecting a finish stationary contact of said one switch means with the corresponding finish stationary contact of all said other switch means when said switch means are in the parallel switch position, whereby all of said winding sections are in multiple.

5. In the combination defined by claim 4 wherein the start rotatable contact of at least one of said switch means in the series switch position bridges one of the start stationary contacts engaged by it in the parallel switch position and said finish stationary contact connected to said conductor means for interconnecting said finish stationary contacts and cascades the winc'liri sections associated therewith with the winding sections of the other switch means.

6. In the combination defined by claim 5 wherein one of said winding sections has a tap connected to said adjacent stationary contact of one of said switch means engaged by said rotatable finish contact means in the series switch position and wherein the start terminal of said one winding section having said tap is floating.

7. In the combination defined by claim 5 wherein said plurality of switch means includes a pair of switch means and said linkage is a four bar linkage which simultaneously operates said pair of switch means.

8. In combination with a transformer having a plurality of winding sections,

first switch means for alternately connecting a plurality of said winding sections in series and in parallel,

second switch means for alternately connecting a different plurality of said winding sections in series and in parallel,

parallel crank, four bar linkage means for simultaneously operating said first and second switch means between series and parallel positions,

each switch means having a plurality of start stationary contacts connected to the start terminals of the corresponding plurality of winding sections and a plurality of finish stationary contacts connected to the finish terminals of said winding sections and having start and finish rotatable contact means operated by said linkage means and adapted to respectively bridge said plurality of start and said plurality of finish stationary contacts in the switch parallel position, whereby the plurality of winding sections are connected in parallel, and are also adapted in the series switch position to disengage from all but one of said plurality of stationary contacts and to bridge said one stationary contact with an adjacent stationary contact and connect the plurality of winding sections associated with the switch in series, conductor means to interconnect a start stationary contact of said first switch means with a start stationary contact of said second switch means and to also interconnect a finish stationary contact of said first switch means with a finish stationary contact of said second switch means when both switch means are in the parallel switch position, whereby said winding sections are in multiple, said start rotatable contact means of said second switch means in the series switch position bridging one of the start stationary contacts engaged by it in the parallel switch position and said adjacent finish stationary contact connected to said conductor means for interconnecting said finish stationary contacts and cascading all of said winding sections.

9. In the combination defined by claim 8 wherein the start terminal of one of said different plurality of winding sections is floating and said one Winding section has a tap connected to said start stationary contact of said sec- 0nd switch means bridged by said finish rotatable contact means in the series switch position.

10. In combination with five transformer Winding sections, first and second switches each of which has eight stationary contacts arranged in a circle and rotatable start and finish contact means movable between a parallel position wherein said start contact means bridges the first, second and third of said stationary contacts and said fin ish contact means bridges the fifth, sixth and seventh of said stationary contacts and a series position wherein said start contact means bridges the third and fourth of said stationary contacts and said finish contact means bridges the seventh and eighth of said stationary contacts, the start terminals of the first, second and third winding sections being connected to the first, second and third stationary contacts of said first switch and the finish terminals thereof being connected to the seventh, fourth and fifth stationary contacts of said first switch, respectively, jumper conductors connecting the second and eighth and also connecting the fourth and sixth stationary contacts of each of said switches, conductor means connecting the first stationary contacts of both of said switches, conductor means connecting the fifth stationary contacts of both of said switches, the start terminals of the fourth and fifth winding sections being connected to the third and second stationary contacts respectively of said second switch and the finish terminals thereof being connected to the seventh and fifth stationary contacts respectively of said second switch, and parallel crank, four bar linkage means for simultaneously operating said first and second rotatable contact means of both of said switches between said series and 10 parallel positions.

8 References Cited UNITED STATES PATENTS 1,831,886 11/1931 Ross 336-147XR 2,466,3 88 4/ 1949 Cuthbertson et a1. 323-49 XR 2,118,291 5/1938 Bollrnan 336147 XR LEWIS H. MYERS, Primary Examiner.

T. J. KOZMA, Assistant Examin'r.

US. Cl. X.R. 32349 

